We don't like to publish half-complete accessory reviews, but in the case of Sennheiser's new BW900 Bluetooth Wireless Office Headset Solution ($390), an ultra-deluxe wireless earpiece, we're making an exception. For reasons explained below, we're not rating the BW900 at this time, but because of certain impressive features it includes for iPhone users, we wanted to let you know some of our findings in advance of a final letter grade.

Unlike all of the other iPhone-compatible Bluetooth wireless headsets we’ve tested, Sennheiser’s approach with the BW900 is intended to be holistic: this is a headset that’s supposed to be used with your mobile phone, and also with a land line. If the latter part doesn’t make sense at first, here’s the concept: this headset comes with a charging cradle and power supply that you are supposed to hook up to a phone line, then use to answer incoming land calls. It also pairs with your iPhone (or other cell phone) to answer incoming mobile calls.

As with all Bluetooth headsets we’ve tested, BW900 includes a rechargeable battery, but unlike most competitors, the battery’s actually user-removable. Why? For business applications. Taking advantage of the charging cradle’s potential, Sennheiser includes both a place to dock BW900 and a charging bay for a second battery, touting the device’s ability to maintain a call in progress—say, a protracted conference call or legal negotiation you don’t want to hang up on—while the battery’s being swapped. Since the BW900’s battery runs for 4-5 hours of talk time depending on your distance from the cradle, you probably won’t need this feature unless you start a call with a partially discharged battery, but it’s an option. One battery is included, along with a dummy piece of plastic that fills the battery bay hole when not in use. Sennheiser sells additional batteries for $38 each; like the BW900, which is already being significantly discounted, they will most likely be widely available for less.

There are some other major changes to what we’ve come to understand as the “standard Bluetooth headset mold.” Sennheiser, for instance, makes no compromises on size in order to achieve unusually impressive audio quality: the microphone extends via gooseneck-style memory wire all the way down to your mouth, where it’s either exposed or covered by a foam windscreen, and the slightly rubber-covered ear speaker (with three sizes of covers) pivots to match the shape of your ear. By comparison with most headsets we’ve tested, BW900 consequently winds up looking somewhat bizarre—like an oversized navy blue and silver toy—and doesn’t fit neatly into a pocket for out-and-about use like its competitors. But there’s a surprise.

It actually feels good on your ear. You wouldn’t expect that from the size, but it’s not heavy or hard to put on. The ear speaker slides outwards to let you slip BW900 on, then inwards to rest close enough to your ear canal to let you hear your callers without a problem. Sennheiser’s covers don’t use a lot of rubber or special padding, but they don’t have to, as this is more like having a small, good speaker right next to your ear than trying to squeeze something inside. As surprising as it was to us by comparison with other, more isolating headsets we’ve tested, we liked the sound and the fit.

We were especially impressed with the microphone’s performance. With only rare exceptions, when we’ve used BW900 with the iPhone, callers have told us that the pairing actually sounds better than the iPhone itself in handset or speakerphone mode, and most callers agree that the sound is better than any other Bluetooth headset we’ve tested. They’ve described the sound as very easy to understand and properly equalized—all signs that Sennheiser’s touted digital signal processing, microphone, and earpiece are working as promised, and better than competitors.

How does it compare with the Aliph Jawbone, which callers have consistently described as the best-sounding headset of our prior review pack? Under normal usage conditions with mild ambient sound, one iLounge editor said that the BW900 sounded “50% better” so long as the microphone was properly positioned near our mouths, with the microphone and optional but included black foam windscreen creating sound that was indoor land line quality even when outdoors in the wind. Callers told us that the BW900 made the Jawbone’s otherwise impressive audio sound comparatively mechanical. We were also very impressed with BW900’s performance under stressful, high background noise conditions. Sennheiser appears to have maximized its microphone for near-distance voice pickup, properly equalized the sound, and filtered out ambient sounds—in one test, we walked next to an active air conditioning unit and our caller described the sound as almost identical to a non-noise environment, only with a slight hum.

The rare exceptions are infrequent calls that have started with much-degraded sound on both ends, rendering callers and us incomprehensible. We’re not entirely sure whether that’s from the iPhone or the BW900, but we have tended to suspect the latter. In any case, ending the call and starting another immediately thereafter—without any Bluetooth re-synchronization—always fixes the issue. As with all of the headsets we’ve tested, initial pairing with the iPhone was simple, as well.

Also of note is BW900’s wireless power. Most of the headsets we’ve tested are rated for 33-foot broadcasting distances, but Sennheiser went with a more powerful Bluetooth standard, and the results are pretty positive: it promises a 300-foot broadcasting range when used with the desktop base, while with the iPhone, we found that it worked from distances of roughly 40 feet away—the best we’ve yet seen—degrading in sound quality only at the end of that range. By contrast with options such as Apple’s iPhone Bluetooth Headset, which is twig-like in size but also in Bluetooth broadcasting power, the BW900 is a champ.

Apart from the $390 asking price, all of this should be great news. There’s only one part of the equation that doesn’t mesh with the rest: the desktop charging and calling unit. For reasons that we expect are technical—we asked Sennheiser for comment but didn’t get a clearer response—the BW900 doesn’t work exactly the way some people might expect as a land line phone. Specifically, you can’t connect the desktop box directly to your land line and start answering calls: instead of an RJ-11 connector, BW900’s box uses RJ-H connectors, which are designed to connect with an existing wired telephone. (Oddly, there is one RJ-11 port on the bottom, but it’s designed to be connected to other optional accessories, not to a land line.) One RJ-H to RJ-H cable is included and comes connected to a port on the unit’s bottom, while the other RJ-H port is empty.

In other words, you need to physically connect BW900 to another telephone, rather than the telephone line, in order to use it. Specifically, the phone has to be a wired telephone rather than a wireless one, because you need to connect BW900 to the handset port of the old phone—the one with the RJ-H connector—so that it will all work. We haven’t used wired phones around here for years, so we didn’t have any with RJ-H connectors to test. But, Sennheiser suggests, fairly, most offices do. And if they don’t, you can buy a separate Sennheiser accessory that connects BW900 to your land line. We haven’t had a chance to try that accessory, and we don’t keep wired phones around, hence, we can’t tell you whether BW900’s land line performance is up to snuff.

Why is this? You’ve probably already noticed from the pictures that BW900 doesn’t have a keypad; its only buttons are multi-functional call answering, volume, and power controls, in the form of a three-position toggle and a depressable button. In other words, you can’t dial a call from your iPhone or land line using the headset. And the base station doesn’t have dialing buttons either; rather, it has a dial to calibrate the volume level correctly for your land line, the ability to store your preferred volume settings, and a couple of top-mounted buttons that also can’t dial for you. For desktop use, you’ll need something with a dialing keypad and the internal components to process land line power, too; that’s where an old-fashioned phone comes in.

For $390, the fact that BW900 can’t serve as both a complete desktop and mobile phone headset replacement without assistance from another device—old phone or Sennheiser “handset lifter” accessory—is a disappointment. But for its intended market, namely business users with extra cash, existing wired phones, and a need for comparatively superb wireless audio performance, BW900 is a strong option. Those looking only for a pocketable, fully portable solution with strong noise cancellation functionality will find Aliph’s Jawbone to be a better alternative given their significant price differences, but for office use, BW900 will be harder to beat on quality than on pricing.

Editors' Note: iLounge only reviews products in "final" form, but many companies now change their offerings - sometimes several times - after our reviews have been published.
This iLounge article provides more information on this practice, known as revving.